Understanding Proper Scaling for 3d Export dimensions
When you exported to .STL, did you check the box next to "Scene Unit"? (Find this on the lower left hand side when you attempt the export).



When a model is 3D printed, it has to be converted to GCode using some other software. Was this software configured correctly to handle inches? 

My advice: save yourself the hassle and just work in millimeters and convert from inches.